X-ray absorption glass



Patented Dec. 24, 1935 UNITED STATES X-RAY ABSORPTION GLASS Frederick Gelstharp, Tarentum, Pa., assignor to Pittsburgh Plate Glass Company, a. corporation of Pennsylvania No Drawing. Application October 13, 1934, Serial No. 748,215

4 Claims.

The invention relates to glass designed to afford protection from X-rays. Such glass contains a relatively high percentage of lead oxide as the screening element, the efficiency of the 5 glass as an X-ray cut-off depending upon the lead oxide content. The object of the present invention is the production of an improved glass of the type specified having a greater X-ray cutoif than it has heretofore been practicable to prol0 duce without making a glass which is too fluid in its molten state for proper casting. Briefly stated, this is accomplished by the use of barium oxide as a cut-01f ingredient to supplement the lead oxide and as a substitute for the alkali which has heretofore been used in lead glass batches as a fluxing agent.

The departure from batches heretofore used will be apparent from a comparison of a typical lead glass batch and glass with the improved batches and glasses, as indicated in the tables which follow.

A standard or typical lead glass X-ray batch, as heretofore used, is as follows:

Parts Sand 1000 Lead oxide 1734 Potassium nitrate 280 Antimony oxide 10 Total 3024 An ultimate analysis of the glass produced from the foregoing batch shows the following result:

Percent SiOz silicon dioxide 34.78 PbO lead oxide 60.35 Potassium oxide 4.52 Antimony oxide .35

Parts Sand 1000 Barium carbonate Barium nitrate 120 Lead oxide 1984 5', Antimony oxide 10 Total 3173 It will be noted on comparison of the foregoing batch with the preceding one that no alkali is 60 used, the barium compounds acting as fluxing agents, and that the proportion of lead oxide is increased.

An ultimate analysis of the glass produced from the foregoing batch shows the following result:

Percent 5 SiOz silicon dioxide 32.1 BaO barium oxide 5.3 PbO lead oxide 62.1 Sb205 antimony oxide .5 10

This glass presents substantial advantages over standard lead glass, such as that given in the first analysis. It has no greater fluidity in the molten 15 state, and at the same time, the X-ray cut-off is substantially higher, due to the higher percentage of lead which the use of the barium compounds permits and to the added cut-off effect of the barium which replaces the potassium (or 20 other alkali metal which might be used in place of the potassium) the cut-off effect of the barium being several times that of the alkali metal.

An alternative batch for producing a modiflca An ultimate analysis of the glass produced 35 from the foregoing batch is as follows:

Percent SiO2 silicon dioxide 32.12

BaO barium oxide 14.63 PbO lead oxide 52.61 40 SbzOs antimony oxide .64

This glass is superior to standard lead glass for the reasons recited in connection with the first 45 form of the improved glass. Various other modiflcations of the improved glass are possible involving variations of the relative amounts of barium and lead from the formulas given, the essential feature of the improvement being the 5 substitution of the barium compound or compounds for the whole or major portion of the alkali which has heretofore been regarded as necessary in the production of lead glasses.

What I claim is: 5

1. An X-ray absorption glass formed by fusing a glass batch substantially free from alkali and containing approximately 50 to per cent of lead oxide and from 4 to 15 per cent of barium O de.

% emeo ooo 2. An X-my absorption glass formed by fusing a. glass batch substantially free from alkali and containing about 62 per cent of lead oxide anfi about 5 per cent of barium oxide.

3. An X-rey absorption glass substantially free from alkali metal and comprising lead oxide and barium oxide totaling upwards of 60 per cent of the weight of the glam.

41. An X-ray absorption glass batch substantlally free from alkali metal and including lead oxide, barium carbonate and barium nitrate with the lead oxide comprising at least 50 per cent of the weight of the batch.

FREDERICK GELSTHARP. 

